CVE-2025-39759 Affecting linux-6.1 package, versions <6.1.153-1~deb11u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.04% (10th percentile)

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  • Snyk IDSNYK-DEBIAN11-LINUX61-13542132
  • published14 Oct 2025
  • disclosed11 Sept 2025

Introduced: 11 Sep 2025

CVE-2025-39759  (opens in a new tab)

How to fix?

Upgrade Debian:11 linux-6.1 to version 6.1.153-1~deb11u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

btrfs: qgroup: fix race between quota disable and quota rescan ioctl

There's a race between a task disabling quotas and another running the rescan ioctl that can result in a use-after-free of qgroup records from the fs_info->qgroup_tree rbtree.

This happens as follows:

  1. Task A enters btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan();

  2. Task B enters btrfs_quota_disable() and calls btrfs_qgroup_wait_for_completion(), which does nothing because at that point fs_info->qgroup_rescan_running is false (it wasn't set yet by task A);

  3. Task B calls btrfs_free_qgroup_config() which starts freeing qgroups from fs_info->qgroup_tree without taking the lock fs_info->qgroup_lock;

  4. Task A enters qgroup_rescan_zero_tracking() which starts iterating the fs_info->qgroup_tree tree while holding fs_info->qgroup_lock, but task B is freeing qgroup records from that tree without holding the lock, resulting in a use-after-free.

Fix this by taking fs_info->qgroup_lock at btrfs_free_qgroup_config(). Also at btrfs_qgroup_rescan() don't start the rescan worker if quotas were already disabled.

CVSS Base Scores

version 3.1